Positive displacement apparatus for selectively translating expander tool downhole

ABSTRACT

The present invention provides a positive displacement apparatus for selectively translating a completion tool, such as an expander tool, downhole. The positive displacement apparatus comprises a set of three essentially concentric tubular members. The three tubulars represent (1) an outer sleeve, (2) an inner mandrel, and (3) a middle displacement piston between the sleeve and the mandrel. These three tubular members are nested within the expandable liner or other tubular to be expanded within a wellbore. A fluid transfer chamber is provided below the middle displacement piston. Rotation of the positive displacement apparatus serves to draw fluid into the fluid transfer chamber. This fluid, in turn, is pumped into a fluid transfer channel and forces the displacement piston upward between the outer sleeve and the inner mandrel. The displacement piston then acts against the rotary expander tool. In this manner, the displacement piston translates the rotary expander tool axially within the wellbore.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to methods for wellbore completion.More particularly, the invention relates to an apparatus for selectivelytranslating a completion tool, such as an expander tool, downhole.

[0003] 2. Description of the Related Art

[0004] Hydrocarbon and other wells are completed by forming a boreholein the earth and then lining the borehole with steel pipe or casing toform a wellbore. After a section of wellbore is formed by drilling, asection of casing is lowered into the wellbore and temporarily hungtherein from the surface of the well. Using apparatus known in the art,the casing is cemented into the wellbore by circulating cement into theannular area defined between the outer wall of the casing and theborehole. The combination of cement and casing strengthens the wellboreand facilitates the isolation of certain areas of the formation behindthe casing for the production of hydrocarbons.

[0005] It is common to employ more than one string of casing in awellbore. In this respect, a first string of casing is set in thewellbore when the well is drilled to a first designated depth. The firststring of casing is hung from the surface, and then cement is circulatedinto the annulus behind the casing. The well is then drilled to a seconddesignated depth, and a second string of casing, or liner, is run intothe well. The second string is set at a depth such that the upperportion of the second string of casing overlaps the lower portion of thefirst string of casing. The second liner string is then fixed or “hung”off of the existing casing by the use of slips which utilize slipmembers and cones to wedgingly fix the new string of liner in thewellbore. The second casing string is then cemented. This process istypically repeated with additional casing strings until the well hasbeen drilled to total depth. In this manner, wells are typically formedwith two or more strings of casing of an ever decreasing diameter.

[0006] Apparatus and methods are emerging that permit tubulars to beexpanded in situ. The apparatus typically includes expander tools thatare run into the wellbore on a working string. The expander toolsinclude a plurality of expansion assemblies that are urged radiallyoutward into contact with a tubular therearound. The expansionassemblies typically comprise a piston disposed within a recess of theexpander tool body, and a roller member positioned on or above anexternal piston surface. In some arrangement's, the expansion assembliesare urged outward from the body of the expander tool by mechanicalforce. More commonly, the back surface of the expansion assembly isexposed to hydraulic pressure from within the bore of the tool. Fluidpressure is provided either by injecting fluid under pressure into thewellbore from the surface, or by activating a dedicated fluid reservoirassociated with the tool.

[0007] As sufficient pressure is generated on the piston surface behindthe expansion assemblies, the tubular being acted upon by the expandertool is expanded past its point of elastic deformation. In this manner,the inner and outer diameter of the tubular is increased in thewellbore. By rotating the expander tool in the wellbore and/or movingthe expander tool axially in the wellbore with the expansion assembliesactuated, a tubular can be expanded into plastic deformation along apredetermined length in a wellbore.

[0008] Multiple uses for expandable tubulars are being discovered. Forexample, an intermediate string of casing can be hung off of a string ofsurface casing by expanding an upper portion of the intermediate stringinto frictional contact with the lower portion of surface casingtherearound. This allows for the hanging of a string of casing withoutthe need for a separate slip assembly as described above. Additionalapplications for the expansion of downhole tubulars exist, such as theuse of an expandable sand screen.

[0009] There are problems associated with the expansion of tubulars. Oneproblem particularly associated with the use of rotary expander tools isthe likelihood of obtaining an uneven expansion of a tubular. In thisrespect, the inner diameter of the tubular that is expanded tends toinitially assume the shape of the compliant rollers of the expandertool, including imperfections in the rollers. Moreover, as the workingstring is rotated from the surface, the expander tool may temporarilystick during expansion of a tubular, then turn quickly, and then stopagain. This spring-type action in the working string further createsimperfections in the expansion job.

[0010] Another obstacle to smooth expansion relates to the phenomenon ofpipe stretch. Those of ordinary skill in the art will understand thatraising a working string a selected distance at the surface does notnecessarily translate into the raising of a tool at the lower end of aworking string by that same selected distance. The potential for pipestretch is great during the process of expanding a tubular. Once theexpander tool is actuated at a selected depth, an expanded profile iscreated within the expanded tubular. This profile creates an immediateobstacle to the raising or lowering of the expander tool. Merely raisingthe working string a few feet from the surface will not, in manyinstances, result in the raising of the expander tool; rather, it willonly result in stretching of the working string. Applying furthertensile force in order to unstick the expander tool may cause a suddenrecoil, causing the expander tool to move uphole too quickly, leavinggaps in the tubular to be expanded.

[0011] The same problem exists in the context of pipe compression. Inthis respect, the lowering of the working string from the surface doesnot typically result in a reciprocal lowering of the expander tool atthe bottom of the hole. This problem is exacerbated by pipe drag causedby friction between the drill pipe and the casing. Because of pipe drag,it is not known how much weight is actually reaching the tools downhole. The overall result of these drag problems is that the innerdiameter of the expanded tubular may not have a uniform circumferencealong the desired length.

[0012] There is a need, therefore, for an improved apparatus forexpanding a portion of casing or other tubular within a wellbore.Further, there is a need for an apparatus which will aid in theexpansion of a tubular downhole and which reduces the potential ofpipe-stretch/pipe-compression by the working string. Correspondingly,there is a need for a method for expanding a tubular which avoids therisk of uneven expansion of the tubular caused by pipe-stretch incidentto raising the working string. Still further, a need exists for anapparatus which will selectively translate a completion tool such as arotary expander tool axially downhole without requiring that the workingstring be raised or lowered.

[0013] There is yet a further need for an apparatus which translates arotary expander tool by means of a piston selectively driven throughpositive displacement.

SUMMARY OF THE INVENTION

[0014] The present invention provides an apparatus and method forselectively translating a completion tool, such as an expander tool,downhole. According to the present invention, a translation apparatus isintroduced into a wellbore. The translation apparatus is lowereddownhole on a working string along with an expander tool, and along witha lower string of casing or other tubular to be expanded. The expandertool includes compliant rollers which are expandable radially outwardagainst the inner surface of the tubular upon actuation.

[0015] The translation apparatus of the present invention utilizespositive displacement to translate the expander tool. The positivedisplacement translation apparatus first defines a set of threeessentially concentric tubular members which reside below the expandertool. The three concentric tubulars represent (1) an outer sleeve, (2)an inner mandrel, and (3) a middle displacement piston nested betweenthe sleeve and the mandrel. These three tubular members are disposedwithin the expandable liner or other tubular to be expanded.

[0016] A fluid transfer chamber is provided below the middledisplacement piston. Rotation of the positive displacement apparatusserves to draw fluid into the fluid transfer chamber. This fluid isapplied against the base of the displacement piston in order to forcethe displacement piston upward between the outer sleeve and the innermandrel. This, in turn, causes the displacement piston to act againstthe rotary expander tool. In this manner, the displacement pistontranslates the expander tool incrementally upward within the wellbore.

[0017] In order to fill the fluid transfer chamber with fluid, apositive displacement mechanism is provided. First, a stator member isprovided below the middle displacement piston. The stator member has atop face at its top end configured in a wave form. In one aspect, thewave form is sinusoidal. At the same time, a rotor piston is providedbelow the displacement piston. The rotor piston has a bottom face whichrides upon the wave form face of the stator member. Preferably, thebottom face of the rotor piston also has a sinusoidal wave form shape.Rotation of the expander tool and the positive displacement apparatus,including the rotor piston, serves to reciprocate the rotor piston in anup-and-down manner. By this reciprocating motion, fluid is drawn intothe fluid transfer chamber and fed against the base of the displacementpiston. This, in turn, causes the expander tool to be translatedupwardly within the wellbore. In this manner, the expander tool can beraised without raising the working string itself.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] So that the manner in which the above recited features of thepresent invention are attained and can be understood in detail, a moreparticular description of the invention, briefly summarized above, maybe had by reference to the appended drawings. It is to be noted,however, that the appended drawings illustrate only typical embodimentsof this invention and are therefore not to be considered limiting of itsscope, for the invention may admit to other equally effectiveembodiments.

[0019]FIG. 1 is a cross-sectional view of a wellbore having an upperstring of casing, and a lower string of casing being lowered into theupper string of casing. In this view, the lower string of casing servesas the expandable tubular. Also depicted in FIG. 1 is a positivedisplacement apparatus of the present invention for translating anexpander tool.

[0020]FIG. 2 is a more detailed view of a scribe as might be placed inthe lower string of casing. The scribe serves as a point of structuralweakness in the lower string of casing, permitting severance uponexpansion of the casing.

[0021]FIG. 3 is an enlarged view of the fluid transfer chamber in anexemplary positive displacement apparatus of the present invention.

[0022]FIG. 4 is a cross-sectional view of a positive displacementapparatus of the present invention, taken across line 4-4 of FIG. 1.

[0023]FIG. 5 is a cross-sectional view of the positive displacementapparatus of FIG. 1. In this view, oil is being transferred from thefluid transfer chamber, up the transfer chamber channel, and into thepiston feed channel. Visible in this view is the initial translation ofthe middle displacement piston.

[0024]FIG. 6 presents an exploded view of an expander tool as might betranslated by the positive displacement pump/piston apparatus of thepresent invention.

[0025]FIG. 7 presents a portion of the expander tool of FIG. 5 incross-section, with the view taken across line 7-7 of FIG. 6.

[0026]FIG. 8 depicts the wellbore of FIG. 1. In this view, the expandertool has been actuated so as to begin expanding the lower string ofcasing. Further, the torque anchor has been actuated so as to stabilizethe lower string of casing and to prevent rotational movement duringexpansion.

[0027]FIG. 9 depicts the wellbore of FIG. 8. In this view, the expandertool remains actuated by hydraulic pressure from the surface. Theworking string has been rotated so as to begin raising the expander toolwithin the wellbore. In this respect, rotation of the positivedisplacement apparatus serves to actuate the piston within theapparatus. This in turn, causes the expander tool to be translatedco-axially within the wellbore.

[0028]FIG. 10 depicts the wellbore of FIG. 9. Here, the expander toolhas been raised further within the wellbore so as to expand the lowerstring of casing into the surrounding upper string of casing along adesired length. The portion of the lower string of casing having ascribe has been expanded, causing severance of the lower string ofcasing.

[0029]FIG. 11 is a sectional view of the wellbore of FIG. 10. In thisview, the torque anchor and the expander tool have been de-actuated andthe lower collet has been released from the liner. Also, the expansionassembly is being removed from the wellbore. Removal of the expansionassembly brings with it the severed upper portion of the lower casingstring.

[0030]FIG. 12 is a sectional view of the wellbore of FIG. 11, with thepositive displacement apparatus of the present invention having beenremoved. In this view, the lower string of casing has been expanded intofrictional and sealing engagement with the upper string of casing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0031]FIG. 1 presents a cross-sectional view of a wellbore 100 having anupper string of casing 110 and a lower string of casing 120. The lowerstring of casing 120, or liner, is being lowered into the wellbore 100co-axially with the upper string of casing 110. The lower string ofcasing 120 is positioned such that an upper expandable portion 120E ofthe lower string of casing 120 overlaps with a lower portion 110L of theupper string of casing 110.

[0032] In the example of FIG. 1, the lower string of casing 120 servesas an expandable tubular. The lower string of casing 120 will be hungoff of the upper string of casing 110 by expanding an upper portion 120Eof the lower string of casing 110 into the lower portion 110L of theupper string of casing 110. However, it is understood that the apparatusand method of the present invention may be utilized to expand downholetubulars other than strings of casing.

[0033] A sealing member 222 is preferably disposed on the outer surfaceof the lower string of casing 120. In one embodiment, the sealing member222 defines a matrix formed in grooves (not shown) on the outer surfaceof the lower string of casing 120. However, other configurations arepermissible, including one or more simple rings formed circumferentiallyaround the lower string of casing 120. In the arrangements of FIG. 1, asingle ring 222 is shown.

[0034] The sealing member 222 is fabricated from a suitable materialbased upon the service environment that exists within the wellbore 100.Factors to be considered when selecting a suitable sealing member 222include the chemicals likely to contact the sealing member, theprolonged impact of hydrocarbon contact on the sealing member, thepresence and concentration of erosive compounds such as hydrogen sulfideor chlorine, and the pressure and temperature at which the sealingmember must operate. In a preferred embodiment, the sealing member 222is fabricated from an elastomeric material. However, non-elastomericmaterials or polymers may be employed as well, so long as theysubstantially prevent production fluids from passing upwardly betweenthe outer surface of the lower string of casing 120L and the innersurface of the upper string of casing 110L after the expandable section120L of the casing 120 has been expanded.

[0035] Also positioned on the outer surface of the lower string ofcasing 120 is at least one slip member 224. The slip member 224 is usedto provide an improved grip between the expandable tubular 120E and theupper string of casing 110L when the lower string of casing 120 isexpanded. In this example, the slip member 224 defines a plurality ofcarbide buttons interspersed within the matrix of the sealing member222. However, any suitable placement of a hardened material whichprovides a gripping means for the lower string of casing 120 into theupper string of casing 110 may be used. For example, a simple pair ofrings having grip surfaces (not shown) formed thereon for engaging theinner surface of the upper string of casing 110 when the lower string ofcasing 120 is expanded would be suitable. The size, shape and hardnessof the slips 224 are selected depending upon factors well known in theart such as the hardness of the inner wall of casing 110, the weight ofthe casing string 120 being hung, and the arrangement of slips 224 used.

[0036] In order to expand the lower string of casing 120 seen in FIG. 1,an expander tool 400 is provided. An expander tool as might be used inthe expansion assembly is seen more fully in FIG. 6. FIG. 6 is anexploded view of an exemplary expander tool 400. FIG. 7 presents thesame expander tool 400 in cross-section, with the view taken across line7-7 of FIG. 6.

[0037] The expander tool 400 has a body 402 which is hollow andgenerally tubular. The central body 402 has a plurality of recesses 414to hold a respective roller 416. Each of the recesses 414 has parallelsides and holds a respective piston 420. The pistons 420 are radiallyslidable, one piston 420 being slidably sealed within each recess 414.The back side of each piston 420 is exposed to the pressure of fluidwithin the hollow bore 415 of the tool 400. In this manner, pressurizedfluid provided from the surface of the well can actuate the pistons 420and cause them to extend outwardly whereby the rollers 416 contact theinner surface of the tubular 120L to be expanded.

[0038] It is understood that the expander tool 400 shown in thereferenced illustrations is merely exemplary. Any arrangement for anexpander tool may be employed with the translation apparatus of thepresent invention 100. These include not only hydraulic expander tools,but mechanically activated expander tools as well. Further, the utilityof the present invention is not limited to hydraulical expander toolsthat rely upon hydraulic pressure from the surface, but includeshydraulic expander tools that utilize a dedicated fluid reservoirassociated with the tool. For example, a sealed fluid reservoir may beprovided between concentric tubulars downhole. Fluid from this reservoirmay be applied against the expansion assemblies within an expander tool,thereby urging them outwardly to expand a surrounding tubular.Alternatively, a blended system may be adopted having a mechanicallyadvanced piston or other roller carrier that rides on a ramp, and has ahydraulic assist.

[0039] Disposed within each piston 420 is a roller 416. In oneembodiment of the expander tool 400, rollers 416 are near-cylindricaland slightly barreled. Each of the rollers 416 is supported by a shaft418 at each end of the respective roller 416 for rotation about arespective rotational axis. The rollers 416 are preferably tilted at avery slight angle of approximately two degrees relative to thelongitudinal axis of the tool 400. This aids in translation of theexpander tool upward. In the arrangement of FIG. 6, the plurality ofrollers 416 are radially offset at mutual 120-degree circumferentialseparations around the central body 402. In the arrangement shown inFIG. 6, only a single row of rollers 416 is employed. However,additional rows may be incorporated into the body 402, as shown in FIG.1.

[0040] The rollers 416 illustrated in FIG. 6 have generally cylindricalor barrel-shaped cross sections; however, it is to be appreciated thatother roller shapes are possible. For example, the roller 416 may have across sectional shape that is conical, truncated conical,semi-spherical, multifaceted, elliptical or any other cross sectionalshape suited to the expansion operation to be conducted within thetubular 120. In addition, at least one portion of the roller surface ispreferably tapered. In some instances, solid pads will take the place ofrollers in an assembly.

[0041] The expander tool 400 is preferably designed for use at or nearthe end of a working string 170. In the arrangement of FIG. 1,connection between the working string 170 and the expander tool 400 isby a mandrel 340′. The mandrel 340′ defines an elongated tubular bodythat extends into and through the expander tool 400. The mandrel portionabove the expander tool 400 is shown at 340′, while the mandrel portionbelow the expander tool is shown at 340. The upper mandrel 340′ includesa spline 337 which is received within a profile (not shown) within theexpander tool body 402. In this way, rotation of the working string 170and the upper mandrel 340′ imparts rotation to the expander tool 400. Atthe same time, and as will be described below, the upper mandrel 340′ isable to radially receive the expander tool 400 when the tool 400 istranslated upward by a positive displacement apparatus 300.

[0042] In order to actuate the exemplary expander tool 400 of FIG. 6,fluid is injected into the working string 170. Fluid under pressure thentravels downhole through the working string 170 and into the perforatedtubular bore 415 of the tool 400. From there, fluid contacts the backsof the pistons 420. As hydraulic pressure is increased, fluid forces thepistons 420 outwardly from their respective recesses 414. This, in turn,causes the rollers 416 to make contact with the inner surface of theliner 120L. Fluid finally exits the expander tool 400 through themandrel 340 at the base of the tool 400. The circulation of fluids toand within the expander tool 400 is preferably regulated so that thecontact between and the force applied to the inner wall of the liner120E is controlled. The pressurized fluid causes the piston assembly 420to extend radially to place the rollers 416 into contact with the innersurface of the lower string of casing 120E. With a predetermined amountof fluid pressure acting on the piston surface 420, the lower string ofexpandable liner 120E is expanded past its elastic limits. Of course, asnoted previously, other means for activating the pistons of the expandertool may be employed.

[0043] In the arrangement of FIG. 1, the lower end of the expander tool400 is connected to a positive displacement apparatus 300. The positivedisplacement apparatus 300 generally defines a tubular assembly which isable to translate the expander tool 400 upwardly in the wellbore 100when the expander tool 400 and the positive displacement apparatus 300are rotated.

[0044] In the arrangement shown in FIG. 1, the positive displacementapparatus 300 first comprises a set of three essentially concentrictubular members which reside below the expander tool 400. The threetubulars represent (1) an outer sleeve 330, (2) an inner mandrel 340,and (3) a middle displacement piston 355 nested between the sleeve 330and the mandrel 340. These three tubular members 330, 355, 340 aredisposed proximate the expandable liner 120 or other tubular to beexpanded. Hence, four separate tubulars 120, 340, 355, 330 are disposedessentially concentrically within the upper casing string 100.

[0045]FIG. 4 is a cross-sectional view of a positive displacementapparatus 300 of the present invention, taken across line 4-4 of FIG. 1.The relative placement of the liner string 120 and of the three tubulars340, 355, 330 of the present invention is seen more fully in this view.It can be seen that an annular region is formed between the innermandrel 340 and the displacement piston 355. Likewise, an annular regionis found between the displacement piston 355 and the outer sleeve 330.Also, an annular region is created between the sleeve 330 and the linerstring 120. Finally, a hollow bore 345 is defined within the innermandrel 340.

[0046] Each of the three tubulars 340, 355, 330 of the positivedisplacement apparatus 300 has an upper end and a lower end. The upperend of the displacement piston 355 is connected to the expander tool400. Connection is preferably by a threaded connection.

[0047] In order to impart rotation to the expander tool 400, and asnoted above, a splined connection 337 is provided between the uppermandrel 340′ and the expander tool body 402. The splined connection 337is in the nature of a traveling spline.

[0048] A fluid transfer chamber 348 is provided below the displacementpiston 355. The fluid transfer chamber 348 and its related componentsare seen more fully in the enlarged view of FIG. 3. As shown, the fluidtransfer chamber 348 is defined by the inner mandrel 340 on the inside,and by a fluid transfer chamber housing 346 on the outside. The purposeof the fluid transfer chamber 348 is to serve as a reservoir throughwhich oil may be transferred from the annular space 325 (shown in FIG.4) outside of the sleeve 330 to the base of the displacement piston 355,thereby fluidly forcing the displacement piston 355 upward. The annulus325 is loaded with a clean, lightweight liquid medium such as oil. Acement bushing (not shown) positioned at a lower end of the positivedisplacement apparatus 300 supports the column of fluid outside of thesleeve 330 and within the liner 120. As seen in FIG. 3, the fluidtransfer chamber 348 is placed in fluid communication with the annulus325 by means of an annular feed channel 324. The annular feed channel324 has a through-opening 324′ at one end which is in open communicationwith the annulus 325. At its opposite end, the annular feed channel 324has a check valve opening 324″ which delivers oil to an inflow checkvalve 374.

[0049] The inflow check valve 374 permits oil to flow into the fluidtransfer chamber 348, but does not permit oil to flow out of the fluidtransfer chamber 348. In the arrangement shown in FIG. 3, the inflowcheck valve 374 is a bullet nose check valve. However, any suitableone-way valve may be used.

[0050] As shown in FIG. 3, more than one check valve is employed for thepositive displacement apparatus 300. In addition to the inflow checkvalve 374, an outflow check valve 372 is also provided. As with theinflow check valve 374, the outflow check valve 372 is a one-way checkvalve. However, the outflow check valve 372 permits oil to flow out ofthe fluid transfer chamber 348, but does not permit oil to flow into thefluid transfer chamber 348. In the arrangement shown in FIG. 3, theinflow check valve 372 is a bullet nose check valve. However, anysuitable one-way valve may be used, or none at all. As oil is deliveredthrough the inflow check valve 374, the fluid transfer chamber 348 isfilled. As additional oil is pumped into the fluid transfer chamber 348,pressure is created therein. Ultimately, oil is forced out of the fluidtransfer chamber 348 through the outflow check valve 372. Oil flows fromthe outflow check valve 372 and into a piston feed channel 334. Thisoil, in turn, provides a force against the lower end of the middledisplacement piston 355, forcing it upward with respect to the outersleeve 330 and the inner mandrel 340. Because the displacement piston355 is connected to the lower end of the expander tool 400, upwarddisplacement of the displacement piston 355 translates the expander tool400 upward within the expandable tubular 120E.

[0051] The arrangement of FIG. 3 also presents a transfer chamberchannel 364. The transfer chamber channel 364 provides a path of fluidcommunication between the check valves 374 and 372, and the fluidtransfer chamber 348 itself. In this arrangement, the transfer chamberchannel 364 resides within a fluid transfer channel housing 365. Thefluid transfer channel housing 365 defines the top of the fluid transferchamber 348, and also houses the check valves 374 and 372. It isunderstood, however, that other arrangements may be provided forchanneling fluid from the fluid transfer chamber 348, through theoutflow check valve 372, and against the displacement piston 355.

[0052] A means is needed to draw oil from the annular space 325 into thefluid transfer chamber 348. In the present invention, the drawing of oilis accomplished through positive displacement. In accordance with thepresent invention, a stator member 210 is first provided. The statormember 210, in one aspect, defines a tubular body which is disposedbelow the fluid transfer chamber 348. The stator member 210 has a topsurface which serves as a face 385. The face 385 is configured in a waveform. Preferably, the wave form is sinusoidal. The stator member 210remains stationary, while the mandrel 340′ rotates through it.

[0053] As seen in FIG. 1, a lower portion of the mandrel 340″ extendsbelow the stator 210. This lower mandrel 340″ also rotates in responseto rotation imparted by the working string 170. A swivel, shownschematically as a sub at 150, is positioned between the lower mandrel340″ and the collet 160 to further facilitate rotation of the innermandrel 340 and the lower mandrel 340″.

[0054] Fixed between the fluid transfer chamber 348 and the tubular body210 is a rotor piston 357. The rotor piston 357 is rotated as part ofthe positive displacement apparatus 300. In this respect, a key or othersplined-type connection 335 connects the mandrel 340 to the rotor piston357 to impart rotation to the rotor piston 357. In the arrangement ofFIG. 3, the fluid transfer channel housing 365 also includes separatesplit rings 332 and 362 which provide a locating shoulder between theouter sleeve 330, the fluid transfer channel housing 365, and the innermandrel 340. These split rings 332, 362 ensure that the components ofthe positive displacement apparatus 300 remain axially stationaryrelative to the rotor piston 357. It is understood, however, that thepresent invention is not limited to any particular manner in which therotor piston 357 is connected to the positive displacement apparatus300, so long as the rotor piston 357 is able to reciprocate in responseto the wave form on the face 385 of the stator member 210.

[0055] The rotor piston 357 has an upper end which defines the bottom ofthe fluid transfer chamber 348. The rotor piston 357 further has a lowerend that includes a face 380 configured in a wave form similar to theface 385 on the tubular body 210. The face 380 of the rotor piston 357rides upon the face 385 of the stator member 210 as the rotor piston 357is rotated. Preferably, the rotor piston face 380 and the stator memberface 385 are each sinusoidal, though other wave forms may be used. Thismeans that rotation of the rotor piston 357 by 90 degrees creates asingle stroke length. In the preferred arrangement, the stroke length isapproximately one-half inch (1.27 cm). Thus, rotation of the expandertool 400 and the positive displacement apparatus 300, including therotor piston 357, serves to reciprocate the rotor piston 357 in anup-and-down manner along a stroke length of approximately one-half of aninch. As will be shown, it is this reciprocating stroke that producesthe positive displacement used to translate the expander tool 400.

[0056] As noted, the positive displacement apparatus 300 includes afluid transfer chamber 348. The fluid transfer chamber 348 is sized andconfigured such that reciprocal movement of the rotor piston 357 causestranslational movement of the displacement piston 355. During the firsthalf of the stroke cycle, the rotor piston 357 moves upwards, therebyreducing the volume of the fluid transfer chamber 348. Reduction of thevolume of the fluid transfer chamber 348 extrudes oil from the fluidtransfer chamber 348 and into the piston feed channel 334. Thisinjection of oil moves the displacement piston 355 upward within theexpandable tubular 120E.

[0057] A biasing member 342 is housed inside the fluid transfer chamber348. The biasing member 342 biases the rotor piston 357 in its downwardposition to ensure essentially continuous contact between the bottomface 380 of the rotor piston 357 and the top face 385 of the statormember 210. Preferably, the biasing member 342 is a spring. The spring342 becomes compressed during the first half of the stroke cycle whenthe rotor piston 357 is thrust upward. During the second half of therotor piston's 357 stroke cycle, the rotor piston 357 moves back intophase with the face 385 of the stator member 210. The spring 342 pushesthe rotor piston 357 back downward, re-expanding the volume of the fluidtransfer chamber 348. The second half of the stroke cycle occurs afteran additional 90 degree rotation of the rotor piston 357. This movementdownward of the rotor piston 357 creates a vacuum within the fluidtransfer chamber 348, thereby drawing fluid, e.g., oil, into the chamber348 from the piston-sleeve annulus 325. With continued cycles, thetransfer chamber 348 becomes filled with fluid under pressure.Ultimately, the oil is extruded out of the transfer chamber 348 andagainst the base of the displacement piston 355.

[0058]FIG. 5 presents a cross-sectional view of the positivedisplacement apparatus 300 of FIG. 1. In this view, oil is beingtransferred from the fluid transfer chamber 348, up the transfer chamberchannel 364, and into the piston feed channel 334. Visible in this viewis the initial translation of the middle displacement piston 355.Continued rotation of the positive displacement apparatus 300 will raisethe displacement piston 355 further within the expandable tubular 120E.This, in turn, causes the expander tool 400 to be translated upwardly.In this manner, the expander tool 400 can be raised without raising theworking string 170 itself.

[0059] In order to effectuate the transfer of oil from the annulus 325,into the fluid transfer chamber 348, and against the displacement piston355, it is desirable to utilize various seals between the components ofthe positive displacement apparatus 300. FIG. 5 presents a variety ofseals. These include a first sealing member 356 at the lower end of thedisplacement piston 355. The sealing member 356 creates a fluid sealbetween the displacement piston 355 and the tubulars 330, 340, therebyallowing all the fluid in the piston feed channel 334 to fully act uponthe displacement piston 355. A second sealing member 359 is disposed atthe lower end of the transfer channel housing 365. The second sealingmember 359 creates a fluid tight seal for the transfer channel housing365 between the transfer chamber housing 346 and the mandrel 340,thereby preventing a leakage from the upper end of the fluid transferchamber 348. A third sealing member 358 is disposed at the upper end ofthe rotor piston 357. The sealing member 358 creates a fluid tight sealfor the rotor piston 357 housed between the transfer chamber housing 346and the mandrel 340, thereby preventing any fluid leakage from the lowerend of the fluid transfer chamber 348.

[0060] Seals are additionally positioned inside and outside of the outersleeve 330 at the lower end. First, seal 337 seals the interface betweenthe outer sleeve 330 and the inner mandrel 340. Second, seal 353 sealsthe annular area between the outer sleeve 330 and the fluid transferchannel housing 365. These seals 337, 353 assist in maintaining fluidwithin the annular feed channel 324 during the translation process. Theseals 337, 353 are seen in FIGS. 3 and 5.

[0061] The present invention is not limited in scope to any singlearrangement of seals. In this respect, various means are known forproviding a fluid seal between nested tubulars. Any sealing arrangementmay be utilized, so long as the reciprocation of the rotor piston 357within the fluid transfer chamber 348 is able to draw oil in during afirst stroke, and extrude oil during an opposite second stroke. In thearrangement shown in FIGS. 3 and 5, oil is drawn into the fluid transferchamber 348 on the downstroke, and extruded during the upstroke. Ofcourse, the apparatus 300 can also be configured to draw oil on theupstroke and to discharge on the downstroke.

[0062] In operation, the positive displacement apparatus 300 of thepresent invention is run into the wellbore 100 on the lower end of theworking string 170. As seen in FIG. 1, the positive displacementapparatus 300 is connected to the expander tool 400 at one end. In thearrangement shown in FIG. 1, the apparatus 300 is connected to thebottom of the expander tool 400. However, it will be appreciated thatthe positive displacement apparatus 300 will also function if thepositive displacement apparatus 300 is above the expander tool 400. Inthis regard, the check valves 374, 372 and associated chamber 348 andchannel 364 would be positioned above the displacement piston 355.

[0063] In order to accomplish the expansion operation in a single trip,the working string 170 also is temporarily connected to the lower stringof casing 120. In this manner, the lower string of casing 120 can beintroduced into the wellbore 100 at the same time as the expander tool400 and the apparatus 300. In FIG. 1, a collet 160 is presented as thereleasable connection. The collet 160 is shown near the end of theworking string 170. The collet 160 is landed into a radial profile 165within the lower string of casing 120 so as to support the lower stringof casing 120. The collet 160 is mechanically or hydraulically actuatedas is known in the art, and supports the lower string of casing 120until such time as the lower string of casing 120 has been expandablyset by actuation of the expander tool 400.

[0064]FIG. 8 depicts the wellbore of FIG. 1, in which the expander tool400 has been actuated. It can be seen that an initial portion of thelower string of casing 120 has been expanded. As explained above,actuation of the expander tool 400 is by injection of fluid underpressure into the working string 170. Fluid travels from the surface,down the working string 170, and through the bore 415 of the expandertool 400.

[0065]FIG. 9 depicts the wellbore 100 of FIG. 8. In this view, theexpander tool 400 remains actuated. This allows the expander tool 400 tomove within the expandable tube 120E relative to the running tool collet160. Also, in FIG. 9, the working string 170 has been rotated so as tobegin raising the expander tool 400 within the expandable tubular 120E.As described above, rotation of the working string 170 causes thedisplacement piston 355 and, therewith, the expander tool 400 to betranslated axially within the wellbore 100. FIG. 9 thus demonstrates theexpander tool 400 being raised within the expandable tubular 120E byactuation of the positive displacement apparatus 300.

[0066] It is contemplated in FIG. 1 that rotation of the rotor piston357 and of the expander tool 400 is accomplished by rotating the workingstring, i.e., drill pipe 170, from the surface. However, rotation mayalso be achieved by activation of a downhole rotary motor, such as a mudmotor (not shown).

[0067]FIG. 10 depicts the wellbore 100 of FIG. 9. Here, the actuatedexpander tool 400 has been raised further within the wellbore 100 so asto expand the lower string of casing 120 into the surrounding upperstring of casing 110 along a desired length. This, in turn, results inan effective hanging and sealing of the lower string of casing 120 uponthe upper string of casing 110 within the wellbore 100. Thus, theapparatus 300 enables a lower string of casing 120 to be hung onto anupper string of casing 110 by expanding the lower string 120 into theupper string 110, and without raising or lowering the working string 170from the surface during expansion operations. It is understood, however,that the working string 170 may optionally be raised and lowered whilethe expander tool 400 is still actuated and after the initial expansionhas taken place, i.e., after the expander tool 400 has been initiallyactuated. Using this procedure, the collet 160 would first need to bereleased from the liner 120.

[0068] Following expansion operations, hydraulic pressure from thesurface is relieved, allowing the pistons 420 to return to the recesses414 within the body 402 of the tool 400. The expander tool 400 and thepositive displacement apparatus 300 can then be withdrawn from thewellbore 100 by pulling the run-in tubular 170. FIG. 11 is a partialsection view of the wellbore 100 of FIG. 10. In this view, the expandertool 400 has been de-actuated and is being removed from the wellbore 100along with the positive displacement apparatus 300. In addition, thecollet 160 or other releasable connection must be released from theliner 120, as shown in FIG. 11.

[0069] In one procedure for utilizing the positive displacementapparatus 300 of the present invention, the liner 120 is expanded to itstop end. However, the length of expansion is discretionary. An uppernon-expanded portion 120S of the liner 120 can be severed after aportion 120E is expanded. The severed portion 120S of the lower stringof casing 120 above the expander tool 400 must then be removed from thewellbore 100. To accomplish this, typical casing severance operationsmay be conducted. This would be done via a subsequent trip into thewellbore 100. However, as an alternative shown in FIG. 11, the severedportion 120S of the lower string of casing 120 may be removed from thewellbore 100 at the same time as the expander tool 400 after the collet160 has been released from the liner 120. In order to employ thismethod, a novel scribe 130 is formed on the outer surface of the lowerstring of casing 120.

[0070] An enlarged view of the scribe 130 in one embodiment is shown inFIG. 2. The scribe 130 defines a cut made into the outer surface of thelower string of casing 120. The scribe 130 is preferably placed aroundthe casing 120 circumferentially. The depth of the scribe 130 needed tocause the break is dependent upon a variety of factors, including thetensile strength of the tubular, the overall deflection of the materialas it is expanded, the profile of the cut, and the weight of the tubularbeing hung. The scribe 130 must be shallow enough that the tensilestrength of the tubular 120 supports the weight below the scribe 130during run-in. The arrangement shown in FIG. 2 employs a single scribe130 having a V-shaped profile so as to impart a high stressconcentration onto the casing wall. However, other profiles may beemployed.

[0071] The scribe 130 creates an area of structural weakness within thelower casing string 120. When the lower string of casing 120 is expandedat the depth of the scribe 130, the lower string of casing 120 iscleanly severed. The severed portion 120U of the lower casing string 120can then be easily removed from the wellbore 100. Thus, the scribe 130may serve as a release mechanism for the lower casing string 120. Othermeans for severing the tubular 120 upon expansion may be developed aswell.

[0072] In order to remove the severed portion 120S of the lower stringof casing 120 from the wellbore 100, a second connection must beprovided with the severed portion of the lower string of casing 120. Inthe arrangement of FIGS. 8-11, a releasable connector 124 is shown. Theconnector 124 is demonstrated as a collet 124 to be landed into a radialprofile 125 within the lower string of casing 120. The collet 124 ismechanically or pneumatically actuated as is known in the art, andsupports the severed portion 120S of the lower string of casing 120while the apparatus 300 and the expander tool 400 are being removed fromthe wellbore 100. Removal of the working string 170 with the expandertool 400 brings with it the severed portion 120S of the lower casingstring 120. It is, of course, understood that other means may beemployed for removing a non-expanded upper portion of liner 120, andthat the arrangement shown in FIGS. 8-11 is purely exemplary.

[0073]FIG. 12 is a partial section view of the wellbore 100 of FIG. 11.In this view, the positive displacement apparatus 300 of the presentinvention and the expander tool 400 have been removed. It can be seenthat the expandable portion 120E of the lower string of casing 120 hasbeen expanded into frictional and sealing engagement with the upperstring of casing 110. The seal member 222 and the slip member 224 areengaged to the inner surface of the upper string of casing 110. Further,the annulus 135 between the lower string of casing 120 and the upperstring of casing 110 has been optionally filled with cement, exceptingthat portion of the annulus which has been removed by expansion of thelower string of casing 120E.

[0074] As a further aid in the expansion of the lower casing string 120,a torque anchor 200 may optionally be utilized. The torque anchor 200serves to prevent rotation of the stator 210 during the expansionprocess. The torque anchor 200 shown in FIG. 1 includes radiallyextendable cleating mechanism 240 for engaging the inner surface of thecasing 110. The torque anchor 200 is actuated during initial expansionof the expandable portion 120E of the liner 120. The torque anchor 200may be released after initial expansion, as shown in FIG. 11.

[0075] While the foregoing is directed to embodiments of the presentinvention, other and further embodiments of the invention may be devisedwithout departing from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

1. An apparatus for translating an expander tool axially within awellbore in order to facilitate the expansion of a first tubular into asurrounding second tubular, the apparatus comprising: a fluid chamberhaving a first end and a second end; a displacement piston having afirst end and a second end, the first end of the displacement pistonacting upon the expander tool, and the second end being in communicationwith the fluid chamber; a rotor piston having a first end and a secondend, the first end of the rotor piston sealingly residing within thefluid chamber; and the fluid chamber sized and configured such thatreciprocal movement of the rotor piston causes axial movement of thedisplacement piston within the wellbore.
 2. The apparatus of claim 1,further comprising a fluid medium that is applied under pressure againstthe second end of the displacement piston in order to translate theexpander tool within the wellbore.
 3. The apparatus of claim 2, whereinthe first tubular defines a lower string of casing, and the secondtubular defines an upper string of casing.
 4. The apparatus of claim 3,wherein the rotor piston has a bottom face at its second end, the bottomface having a wave form configuration; and the first end of the rotorpiston is reciprocated axially within the fluid transfer chamber byrotating the rotor piston.
 5. The apparatus of claim 4, furthercomprising a stator member, the stator member having a top face having awave form configuration; and wherein the bottom face of the rotor pistonrides on the top face of the stator member such that rotation of therotor piston causes the rotor piston to reciprocate axially.
 6. Theapparatus of claim 5, wherein the stator member is stationary within thewellbore while the rotor piston is being rotated.
 7. The apparatus ofclaim 6, further comprising a biasing member disposed in the fluidchamber, the biasing member biasing the rotor piston to ensureessentially continuous contact between the bottom face of the rotorpiston and the top face of the stator member.
 8. The apparatus of claim7, further comprising: an inner mandrel, the inner mandrel defining atubular body nested essentially concentrically within the displacementpiston; an outer sleeve, the outer sleeve defining a tubular bodysurrounding the displacement piston such that the displacement piston isnested essentially concentrically within the outer sleeve; and whereinthe fluid medium is loaded in an annular region defined between theexpandable first tubular and the outer sleeve.
 9. The apparatus of claim8, further comprising: an annular feed channel placing the annularregion and the fluid chamber in fluid communication; an inflow valvepermitting fluid to flow from the annular region into the fluid chamber;and an outflow valve permitting fluid to flow from the fluid chamberagainst the second end of the displacement piston in response torotational movement of the rotor piston.
 10. The apparatus of claim 9,wherein the displacement piston is connected to the outer sleeve by asplined connection, allowing the displacement piston to move axiallyrelative to the outer sleeve.
 11. The apparatus of claim 10, wherein thedisplacement piston is connected to the inner mandrel by a splinedconnection, allowing the displacement piston to move axially relative tothe inner mandrel.
 12. The apparatus of claim 9, further comprising atleast one seal at the first end of the rotor piston to provide a fluidseal between the rotor piston and the fluid chamber.
 13. The apparatusof claim 12, further comprising at least one seal at the second end ofthe displacement piston to provide a fluid seal between the displacementpiston and the inner mandrel on an inner surface of the displacementpiston, and between the displacement piston and the outer sleeve on anouter surface of the displacement piston.
 14. An apparatus fortranslating an expander tool axially within a wellbore in order tofacilitate the expansion of an upper portion of a liner string into asurrounding string of casing, the apparatus comprising: a fluid transferchamber having an upper end and a lower end; a displacement pistonhaving an upper end and a lower end, the upper end of the displacementpiston acting upon the expander tool, and the lower end being incommunication with the fluid chamber; an inner mandrel, the innermandrel defining a tubular body nested essentially concentrically withinthe displacement piston; an outer sleeve, the outer sleeve defining atubular body surrounding the displacement piston such that thedisplacement piston is nested essentially concentrically within theouter sleeve; a rotor piston having an upper end and a lower end, theupper end of the rotor piston sealingly residing within the fluidtransfer chamber; oil, the oil loaded in an annular region definedbetween the expandable liner string and the outer sleeve; an annularfeed channel placing the annular region and the fluid chamber in fluidcommunication; an inflow valve permitting the oil to flow from theannular region into the fluid chamber; an outflow valve permitting theoil to flow from the fluid chamber against the lower end of thedisplacement piston in response to rotational movement of the rotorpiston; and the fluid chamber sized and configured such that reciprocalmovement of the rotor piston causes axial movement of the displacementpiston within the wellbore.
 15. The apparatus of claim 14, wherein therotor piston has a bottom face at its lower end, the bottom face havinga wave form configuration; the second end of the rotor piston isreciprocated axially within the fluid transfer chamber by rotating therotor piston;
 16. The apparatus of claim 15, further comprising astationary stator member, the stator member having a top face having awave form configuration; and wherein the bottom face of the rotor pistonrides on the top face of the stator member such that rotation of therotor piston imparts an upstroke and a downstroke to the rotor piston,causing the rotor piston to reciprocate axially within the fluidtransfer chamber such that oil is drawn into the fluid transfer chamberon the downstroke of the rotor piston, and oil is extruded underpressure against the displacement piston on the upstroke, therebyimparting axial movement to the displacement piston and to the expandertool within the wellbore.
 17. The apparatus of claim 16, furthercomprising a spring disposed in the fluid transfer chamber, the springbiasing the rotor piston to ensure essentially continuous contactbetween the bottom face of the rotor piston and the top face of thestator member.
 18. The apparatus of claim 17, wherein the displacementpiston moves axially relative to the outer sleeve.
 19. The apparatus ofclaim 18, wherein the displacement piston moves axially relative to theinner mandrel.
 20. The apparatus of claim 15, further comprising astationary stator member, the stator member having a top face having awave form configuration; and wherein the bottom face of the rotor pistonrides on the top face of the stator member such that rotation of therotor piston imparts a downstroke and an upstroke to the rotor piston,causing the rotor piston to reciprocate axially within the fluidtransfer chamber such that oil is drawn into the fluid transfer chamberon the upstroke of the rotor piston, and oil is extruded under pressureagainst the displacement piston on the downstroke, thereby impartingaxial movement to the displacement piston and to the expander toolwithin the wellbore.
 21. An apparatus for translating an expander toolaxially within a wellbore in order to facilitate the expansion of anupper portion of a liner string into a surrounding string of casing, theapparatus comprising: a fluid transfer chamber having an upper end and alower end; a displacement piston having an upper end and a lower end,the upper end of the displacement piston acting upon the expander tool,and the lower end being in communication with the fluid chamber; a rotorpiston having an upper end and a lower end, the upper end of the rotorpiston sealingly residing within the fluid transfer chamber, and thelower end having a bottom face, the bottom face having a wave formconfiguration; a spring disposed in the fluid transfer chamber, thespring biasing the rotor piston to ensure essentially continuous contactbetween the bottom face of the rotor piston and the top face of thestator member; a stator having an upper face having a wave formconfiguration which mates with the bottom face of the rotor piston; andwherein the bottom face of the rotor piston rides on the top face of thestator member such that rotation of the rotor piston imparts an upstrokeand a downstroke to the rotor piston, causing the rotor piston toreciprocate axially within the fluid transfer chamber such that oil isdrawn into the fluid transfer chamber on the downstroke of the rotorpiston, and oil is extruded under pressure against the displacementpiston on the upstroke, thereby imparting axial movement to thedisplacement piston and to the expander tool within the wellbore. 22.The apparatus of claim 21, further comprising a plurality of checkvalves, the check valves being constructed and arranged to allow the oilto enter the fluid transfer chamber on the downstroke of the rotorpiston, and to exit the fluid transfer chamber on the upstroke of therotor piston.
 23. The apparatus of claim 22, further comprising aplurality of check valves, the check valves being constructed andarranged to allow the oil to enter the fluid transfer chamber on theupstroke of the rotor piston, and to exit the fluid transfer chamber onthe downstroke of the rotor piston.
 24. The apparatus of claim 22,further comprising: an inner mandrel, the inner mandrel defining atubular body nested essentially concentrically within the displacementpiston; an outer sleeve, the outer sleeve defining a tubular bodysurrounding the displacement piston such that the displacement piston isnested essentially concentrically within the outer sleeve; and whereinthe fluid medium is loaded in an annular region defined between theexpandable liner string and the outer sleeve.